To maintain the high degree of reliability that the system offers when communications span distances of several miles, Conspec employs a remote field unit known as a Red Outstation. The Outstation has two major configurations; a Long Distance Accessor and an Accessor Trunk Extender. As its name implies, the P1448 Long Distance Accessor (LDA) gives you the capability to initiate a full trunk line, with a maximum of 128 Accessors, in a remote area of your mine. When there is a great distance separating the central station from the area to be monitored it is often impractical to lay an Accessor Trunk Cable that would have to run for several thousand feet without supporting any Accessors. In this instance an inexpensive telephone line can be used to link the central station to the remote area being monitored. A LDA provides the modem interface and the hardware necessary to drive the remote Accessor trunk.

The LDA also comes equipped with a four-hour battery back up and a watchdog timer to monitor communications on the remote trunk. As an option a dual trunk driver may be supplied in order to support two remote trunks. A dual light-emitting diode display on the front of the LDA indicates whether the unit is being powered from an external AC source or the batteries. To prevent an inadvertent failure due to low battery levels the battery unit will cut out when its power output drops below twenty-three volts. This prevents the battery from being completely drained, ensuring that the system will be fully operational as soon as power is restored.

The P1534 Accessor Trunk Extender (ATE) is a Red Outstation that is used to increase the distance over which Accessor communication can occur. Beyond 8,000 feet, capacitance in the Accessor Trunk Cable causes the signal to loose its shape. This problem can be corrected with the use of a trunk expander. However after 32,000 feet (three in the power circuit is no longer sufficient to drive the signal. When this occurs an ATE is used to boost and reshape the signal allowing communication to continue for another six miles.

Four-hour Battery Back-Up